The varicose vein is a disease that occurs in living body lumens. In each vein in a living body, venous valves for returning blood to the heart against the gravity exist. If a disorder occurs in the venous valves, the backflow of blood occurs and the venous pressure becomes high, so that varicose veins develop due to dilation of veins.
Several methods have been proposed for treatment of the varicose vein, which includes a laser treatment technique of occluding a vein by heat attributed to irradiation with laser light (for example, refer to U.S. Pat. No. 7,524,316). In the laser treatment technique of the related art, an optical fiber is inserted into a vein in which a varicose vein develops. Furthermore, laser light is emitted from the distal surface of the optical fiber and a wall of the blood vessel is irradiated with the emitted laser light to cauterize the wall of the blood vessel.
However, in the laser treatment technique of the related a the laser light is emitted only from the distal surface of the optical fiber. Therefore, a wall of a blood vessel can be carbonized due to local excessive heating of the wall of the blood vessel and the wall of the blood vessel can be broken depending on the case.